It has previously been proposed to provide insert elements which cover grooves and adjust the inserts radially--see, for example, German Pat. No. 640,262. The insert elements are used to clamp flexible printing plates. Adjustment screws for the insert elements are operated by angle gear drives and an adjustment spindle. It is difficult to precisely adjust the insert element radially. Precise adjustment is hardly possible since the insert element must be moved over a distance sufficient to cause the printing plate to be pressed against the edge of the cylinder groove. Shocks and vibrations which occur in operation can be accepted only by engagement of the insert with the edge of the cylinder groove. The adjustment is possible only when the cylinder is stationary.
German Pat. No. 236,935 describes an arrangement which permits adjustment of the height position of an insert element. To adjust the insert element radially with respect to the cylinder with which it is used, in other words the height position of the cylinder, two adjustment screws are provided which engage with one end in the groove of the cylinder, the other end being screwed into the insert element. The adjustment of these screws can be effected only when the insert piece is taken out of the cylinder groove. Thus, only successive trial-and-error placements of the insert element can result in reasonably well adjusted alignment of the insert element, which is extremely timeconsuming. Of course, the adjustment screws can be operated only when the cylinder is stationary.